Dragonstar is a futuristic magic-meets-machine campaign setting created by Fantasy Flight Games for Wizards of the Coast's D20 role-playing game system. The setting describes a galaxy under the dominion of the Dragon Empire. The Dragon Empire is a huge bureaucracy, ruled over by the ten houses of dragons, five chromatic and five metallic, led by Mezzenbone, a red dragon of immense might and evil disposition, who sometimes travels on board The Maleficant, one of the few remaining immense Dreadnought class warship spacecraft.
Across the galaxy, the same fantasy races are found to inhabit countless worlds, sometimes living in great technological civilizations or magically advanced medieval cultures. When the inhabitants of many of these worlds took to the stars by magic or machine (usually both), they were amazed by their similarities. Even their languages were the same, although different dialects had evolved on the various worlds. Both scientists and archmages alike tried to come up with a logical explanation of why most worlds were almost the same, but they were stumped. Eventually, a predominant religious leader of unknown origin emerged and proposed that all the gods of every religion were the same, just different aspects of the twelve "True Gods" and their hybrid faiths.
The Dragonstar setting can easily combine preexisting D20 material and settings. A PC group can be comprised of character races and classes of any combination and be rationally integrated with little work. It is similar to the classic Spelljammer setting by TSR, although Spelljammer was essentially "fantasy in space", with all space travel explained through magic rather than technology, Dragonstar is more science fantasy; fighters use lasers, machine guns, and grenades, and characters fly in starships through solar systems, although things that are impossible due to our current understanding of physics, such as faster-than-light travel between stars, force-fields, and teleportation, require magic.